before-after study
(before and after study, uncontrolled before and after study, uncontrolled before-after study)
— A type of non-randomized study in which health conditions are measured before and after a treatment; … (read more)

bias
(systematic error)
— A type of error that may affect the results of a study because of weaknesses in its design, analysis or reporting.; … (read more)

bias, allocation see allocation bias
(assignment bias, selection bias)
— Bias resulting from the way participants in a study have been allocated to treatment comparison groups.; … (read more)

bias, attrition see attrition bias
(exclusion bias)
— Systematic differences between treatment comparison groups in withdrawals or exclusions of participants from the results of a study.; … (read more)

bias, confirmation see confirmation bias
(myside bias)
— Bias resulting from the tendency to search for, or interpret information in a way that confirms pre-existing ideas, and leads to incorrect conclusions.; … (read more)

bias, disease progression see disease progression bias
— In a study of diagnostic test accuracy, bias which occurs when the time period between the reference standard test and index test is so long that the health condition of interest may have changed between the two tests.; … (read more)

bias, interpretation see spin
(interpretation bias)
— Bias resulting from interpreting the results of a study in a way which goes beyond an objective assessment of the evidence.; … (read more)

bias, lead-time see lead-time bias
— An apparent increase in survival due to detecting a health condition such as cancer at an early stage, when there is no actual effect on survival, just a longer period with the diagnosis.; … (read more)

bias, length-time see length-time bias
(length bias)
— In screening, an apparent increase in survival due to detecting disease earlier than it would otherwise have been detected; … (read more)

bias, performance see performance bias
— Bias resulting from differences in the care provided to the participants in a study, other than the treatments being compared.; … (read more)

bias, reporting see reporting bias
(publication bias)
— Bias resulting from decisions by researchers, or others (e.g. drug companies or journal editors) not to report or publish the results of a study, or not to provide full information about a study; … (read more)

bias, reporting see reporting bias
(publication bias)
— Bias resulting from decisions by researchers, or others (e.g. drug companies or journal editors) not to report or publish the results of a study, or not to provide full information about a study; … (read more)

bias, reporting see reporting bias
(publication bias)
— Bias resulting from decisions by researchers, or others (e.g. drug companies or journal editors) not to report or publish the results of a study, or not to provide full information about a study; … (read more)

bias, risk of see risk of bias
— The likelihood of there being a systematic error (bias) that distorts an effect estimate in treatment comparisons.; … (read more)

bias, sponsor see sponsor bias
— Bias resulting from the conduct of a study, or the interpretation of results, motivated by financial or academic vested interests.; … (read more)

blinding
(masking)
— In treatment comparisons, actions intended to prevent study participants (the people receiving and providing care) or the researchers (or others measuring outcomes) from knowing which participants received which treatment; … (read more)

blinding, double see double blinding
(double masking*)
— Actions intended to prevent two (or more) groups of people involved in a study knowing which participants received which treatment; … (read more)

blinding, single see single blinding*
(single masking)
— Actions intended to prevent one group of people involved in a study knowing which participants received which treatment; … (read more)

blinding, triple see triple blinding*
(triple masking)
— Actions intended to prevent three (or more) groups of people involved in a study from knowing which participants received which treatment; … (read more)

burden
— The negative psychological, financial or time impact of taking a test or treatment; … (read more)